Jethro Bodine you said,
"Paul is telling them it is effectual and applicable to them
as long as they they stay steadfast in faith in that hope, that gospel. Stop doing that and you no longer have the hope and promise the gospel gives (a 'hope' and a 'promise' because it is about things to come). Faith is how you access the hope held out in the gospel. No faith, or no continuing faith--no way to access the hope and promise of the gospel."
I just add that if a person did what you say is rejection of the Savior, they will never, ever, ever be able to be saved again. per Hebrews,
Heb 6:4
for it is impossible for those once enlightened, having tasted also of the heavenly gift, and partakers having became of the Holy Spirit,
Heb 6:5 and did taste the good saying of God, the powers also of the coming age,
Heb 6:6 and
having fallen away, again to renew them to reformation, having crucified again to themselves the Son of God, and exposed to public shame.